Inlet guide vane, compressor, inlet guide vane attachment method, and centrifugal compressor production method

ABSTRACT

An inlet guide vane includes vane main bodies (42) having a pressure surface (S1) and a suction surface (S2) which extend along a radial-direction axial line (Ar). Each of the pressure surface (S1) and the suction surface (S2) has a blade-shaped surface along a surface of an imaginary blade shape (Pv) having a blade-like cross-sectional shape. At least one of the pressure surface (S1) and the suction surface (S2) has a thin portion-forming surface (St) which recedes toward an inside of the imaginary blade shape (Pv) more than the surface of the imaginary blade shape (Pv).

TECHNICAL FIELD

The present invention relates to an inlet guide vane, a compressor, an inlet guide vane attachment method, and a centrifugal compressor production method.

Priority is claimed on Japanese Patent Application No. 2015-209875, filed on Oct. 26, 2015, the content of which is incorporated herein by reference.

BACKGROUND ART

Among compressors that are used in, for example, turbo refrigerators, there are compressors in which movable guide blades (inlet guide vanes) are set in a suction port for suctioning external air. A plurality of inlet guide vanes is provided in the circumferential direction at intervals on the inner diameter side of a circular suction port. Specifically, the respective inlet guide vanes are attached to attachment portions arrayed in the circumferential direction of the suction port.

In addition, in compressors having a constitution in which no inner cylinder is provided in a suction port, each inlet guide vane has a shape that extends from an inner circumferential surface of the suction port to the center of the suction port. That is, in the vicinity of the center of the suction port, a plurality of inlet guide vanes gather from the outside in the radial direction of the suction port (refer to Patent Document 1).

CITATION LIST Patent Literature

[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2013-245575

SUMMARY OF INVENTION Technical Problem

Meanwhile, when the above-described inlet guide vanes are attached to the suction port, the respective inlet guide vanes are inserted into the attachment portions provided in the suction port from the inside of the suction port. Here, when a specific number or more of inlet guide vanes are inserted, in order to prevent an inlet guide vane to be attached from interfering with other inlet guide vanes that have been already attached, it is necessary to insert a portion of an inlet guide vane on the inside in the radial direction into a gap between other adjacent inlet guide vanes and then move the inlet guide vane toward the outside in the radial direction.

Therefore, the thickness of the inlet guide vane needs to be smaller than the gap between the inlet guide vanes. On the other hand, from the viewpoint of improving the performance of the inlet guide vane, it is vital to set the thickness of the respective inlet guide vanes to be thick. Therefore, there is an intensifying demand for an inlet guide vane capable of satisfying both the performance of the inlet guide vane and the ease of assembly.

The present invention provides an inlet guide vane having sufficient performance and ease of assembly, a compressor, an inlet guide vane attachment method and a centrifugal compressor production method.

Solution to Problem

An inlet guide vane according to a first aspect of the present invention includes vane main bodies having a pressure surface and a suction surface which extend in a radial direction of a rotary shaft, each of the pressure surface and the suction surface has a blade-shaped surface along a surface of an imaginary blade shape having a blade-like cross-sectional shape, and at least one of the pressure surface and the suction surface has a thin portion-forming surface which recedes toward an inside of the imaginary blade shape more than the surface of the imaginary blade shape.

According to this constitution, the thin portion-forming surface is formed on at least one of the pressure surface and the suction surface of the vane main body. Therefore, when the plurality of vane main bodies is arrayed on an inner circumferential surface of a casing (suction port) of a compressor, it is possible to easily put a vane main body that is to be attached soon into a gap formed between vane main bodies that have already been attached. Furthermore, the blade-shaped surface is formed along the surface of the imaginary blade shape in a portion excluding the thin portion-forming surface. Therefore, it is possible to sufficiently ensure the performance of the inlet guide vane.

In the inlet guide vane according to a second aspect of the present invention, in the first aspect, the vane main body may have a front end surface on an end portion on an inside in the radial direction, the thin portion-forming surface may be formed in a front end-side region connected to the front end surface on one of the pressure surface and the suction surface, and the blade-shaped surface on one of the pressure surface and the suction surface may be formed in a base end-side region of the thin portion-forming surface on an outside in the radial direction.

According to this constitution, the thin portion-forming surface is formed on a front end side of the vane main body. Therefore, when the plurality of vane main bodies is arrayed on the inner circumferential surface of the casing (suction port) of the compressor in a state in which the front ends thereof are gathered, it is possible to easily put a vane main body that is to be attached soon into a gap formed between vane main bodies that have been already attached on the inside in the radial direction.

In the inlet guide vane according to a third aspect of the present invention, in the second aspect, the thin portion-forming surface may be formed along a blade central line of the imaginary blade shape.

According to this constitution, there is no case in which the vane main body becomes excessively thin due to the provision of the thin portion-forming surface. Therefore, it is possible to improve the ease of assembly of the inlet guide vane while maintaining the structural strength of the vane main body.

In the inlet guide vane according to a fourth aspect of the present invention, in the second aspect, the front end surface may form a blade shape along the imaginary blade shape, and the thin portion-forming surface may be formed so as to, as the thin portion-forming surface runs from an edge portion of one of the pressure surface and the suction surface on the front end surface toward the outside in the radial direction, extend toward the other of the pressure surface and the suction surface.

According to this constitution, there is no case in which the vane main body becomes excessively thin even when the thin portion-forming surface is provided. Therefore, it is possible to more sufficiently ensure the structural strength of the vane main body.

In the inlet guide vane according to a fifth aspect of the present invention, in any one aspect of the second to fourth aspects, one of the pressure surface and the suction surface may have a connection surface that is configured to connect a level difference between the blade-shaped surface and the thin portion-forming surface.

According to this constitution, due to the formation of the connection surface, it is possible to decrease the possibility that the flow of fluid along the pressure surface and the suction surface may separate.

In the inlet guide vane according to a sixth aspect of the present invention, in the first aspect, the thin portion-forming surface may be formed on one of the pressure surface and the suction surface so as to be sandwiched by the blade-shaped surface from both the inside in the radial direction and the outside in the radial direction.

According to this constitution, it is possible to suppress the size of the thin portion-forming surface being smaller compared with a case in which the thin portion-forming surface is formed throughout the entire region including the end portion on the inside in the radial direction on one of the pressure surface and the suction surface. Therefore, it is possible to further decrease the separation of the flow of fluid caused by the formation of the thin portion-forming surface.

In the inlet guide vane according to a seventh aspect of the present invention, in any one aspect of the first to seventh aspects, the imaginary blade shape may become smaller in a similar shape as the blade-like cross-sectional shape runs from the outside in the radial direction to the inside in the radial direction.

According to this constitution, in the region on the outside in the radial direction in which the flow rate of fluid becomes relatively faster, it is possible to relatively significantly ensure the area of the imaginary blade shape. Therefore, it is possible to more effectively guide fluid and improve the efficiency of the inlet guide vane.

In the inlet guide vane according to an eighth aspect of the present invention, in any one aspect of the first to seventh aspects, in the imaginary blade shape, the blade-like cross-sectional shape may form a linearly symmetric shape having the blade central line as a symmetric axis.

According to this constitution, it is possible to efficiently guide fluid using any surface of the pressure surface and the suction surface of the vane main body.

A ninth aspect of the present invention includes the inlet guide vane according to any one aspect of the first to eighth aspects, a casing in which a suction port that is configured to support the inlet guide vane is formed, and an impeller that is configured to compress fluid suctioned from the suction port.

According to this constitution, it is possible to provide a compressor having inlet guide vanes that are easily assembled.

An inlet guide vane attachment method according to a tenth aspect of the present invention is an inlet guide vane attachment method for attaching a plurality of inlet guide vanes to a suction port formed in a casing of a compressor in a circumferential direction of the suction port at intervals, in which, in the inlet guide vane, each of a pressure surface and a suction surface has a blade-shaped surface along a surface of an imaginary blade shape having a blade-like cross-sectional shape, and at least one of the pressure surface and the suction surface has a thin portion-forming surface which recedes toward an inside of the imaginary blade shape more than a surface of the imaginary blade shape, and the attachment method includes a step of attaching a first inlet guide vane to an inner circumferential side of the casing, a step of attaching a second inlet guide vane at an interval with respect to the first inlet guide vane in the circumferential direction, and a step of attaching a third inlet guide vane between the first inlet guide vane and the second inlet guide vane in the circumferential direction, in which, in the step of attaching the third inlet guide vane, a portion of the third inlet guide vane on an inside in a radial direction which includes the thin portion-forming surface is inserted into a gap between the first inlet guide vane and the second inlet guide vane, and then the third inlet guide vane is moved to an outside in the radial direction.

According to this method, it is possible to easily attach a plurality of inlet guide vanes to a suction port formed in a casing of a compressor without causing interference among them.

A centrifugal compressor production method according to an eleventh aspect of the present invention includes a step of preparing the casing and the plurality of inlet guide vanes, the respective steps of the inlet guide vane attachment method according to the tenth aspect, and a step of attaching a rotary shaft and an impeller to an inner portion of the casing.

According to this method, it is possible to obtain a centrifugal compressor including inlet guide vanes which can be easily attached and have sufficient performance.

Advantageous Effects of Invention

According to the present invention, it is possible to provide an inlet guide vane having sufficient performance and ease of assembly, a compressor including the same, and an inlet guide vane attachment method.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing a constitution of a centrifugal compressor according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an inlet guide vane according to the first embodiment of the present invention.

FIG. 3 is a view of a vane main body according to the first embodiment of the present invention seen in an axial line As direction.

FIG. 4 is a cross-sectional view in a direction of an arrow IV-IV in FIG. 3.

FIG. 5 is a view of a vane main body according to a second embodiment of the present invention seen in the axial line As direction.

FIG. 6 is a cross-sectional view in a direction of an arrow VI-VI in FIG. 5.

FIG. 7 is a view of a vane main body according to a third embodiment of the present invention seen in the axial line As direction.

FIG. 8 is a cross-sectional view in a direction of an arrow VIII-VIII in FIG. 7.

FIG. 9 is a view of a vane main body according to a fourth embodiment of the present invention seen in the axial line As direction.

FIG. 10 is a cross-sectional view in a direction of an arrow X-X in FIG. 9.

FIG. 11 is a flowchart showing individual steps of a centrifugal compressor production method according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described with reference to drawings. A compressor (centrifugal compressor) according to the present embodiment includes a rotary shaft 29, two impellers (a first impeller 21 and a second impeller 22), a casing 28, and an inlet guide vane V as shown in FIG. 1. The rotary shaft 29 extends along an axial line As. The two impellers (the first impeller 21 and the second impeller 22) are integrally attached to the rotary shaft 29. The casing 28 forms a flow channel for circulating fluid (air) by covering the first impeller 21 and the second impeller 22 from the outer circumferential side. The inlet guide vane V is provided on one side of the casing 28 in an axial line direction.

The casing 28 has a casing main body 28A and a suction casing 30A. In one side of the casing main body 28A in the axial line As direction, a suction port 30 (suction casing 30A) for drawing refrigerant gas from the outside is provided. While described in detail below, the inlet guide vane V capable of changing the angle depending on the operation status is attached to an inner circumferential side of the suction port 30. In the other side of the casing main body 28A in the axial line As direction, a scroll 31 that ejects refrigerant gas is provided. In the casing main body 28A, an inner space 32 that communicates with the suction port 30 and the scroll 31 is formed.

The first impeller 21 and the second impeller 22 are disposed in the inner space 32. The first impeller 21 and the second impeller 22 form a first compression stage and a second compression stage respectively. Each of the first impeller 21 and second impeller 22 has a plurality of blades B that extends from the inside toward the outside in the radial direction with respect to the axial line As.

The plurality of blades B is arrayed in a circumferential direction with respect to the axial line As at intervals. Between a pair of blades B adjacent to each other in the circumferential direction, a flow channel for circulating refrigerant gas is formed. This flow channel gradually curves from the inside toward the outside in the radial direction as the flow channel runs from one side toward the other side in the axial line As direction.

The inner space 32 includes a return flow channel 33 connected to a downstream side of a flow channel of the first impeller 21 and a suction flow channel 34 (inflow flow channel 34) that is configured to connect the return flow channel 33 and an upstream side of a flow channel of the second impeller 22. In the following description, an actual body portion of a centrifugal compressor 2 that forms the return flow channel 33 will be referred to as a return flow channel-forming portion 33A. That is, the return flow channel 33 includes a part of the casing 28 as the return flow channel-forming portion 33A.

The return flow channel 33 circulates refrigerant gas from a flow channel outlet port on the outside of the first impeller 21 in the radial direction toward a flow channel inlet port on the inside of the second impeller 22 in the radial direction. The return flow channel 33 (return flow channel-forming portion 33A) has a return bend portion 36, a straight flow channel 37, return vanes 38, and a middle suction port 41.

A diffuser 35 guides refrigerant gas compressed by the first impeller 21 to the outside in the radial direction. In the diffuser 35, the flow channel area that is seen in the radial direction gradually increases as the flow channel runs from the inside in the radial direction to the outside in the radial direction. On a cross-section including the axial line As, wall surfaces of the diffuser 35 on both sides in the axial line As direction extend in parallel from the inside toward the outside in the radial direction. An end portion of the diffuser 35 on the outside in the radial direction is reversed toward the inside in the radial direction through the return bend portion 36 and is then communicated with the straight flow channel 37. Meanwhile, the wall surfaces of the diffuser 35 on both sides in the axial line As direction do not need to be perfectly parallel to each other at all times and may be substantially parallel to each other.

The return bend portion 36 curves toward the outside in the radial direction in the central portion on a cross-section including the axial line As. In other words, the return bend portion 36 curves in substantially an arc shape having one point on the axial line As side as the center. The straight flow channel 37 extends from an end portion of the return bend portion 36 on the downstream side toward the inside in the radial direction. In the straight flow channel 37, a plurality of return vanes 38 is radially arrayed around the axial line As.

In the suction flow channel 34 of the return flow channel 33 (that is, the flow channel inlet port of the second impeller 22), movable vanes 50 capable of changing the angle depending on the operation status are provided. A plurality of movable vanes 50 is arrayed in the circumferential direction with respect to the axial line As at intervals. The plurality of movable vane 50 is driven by a driving device 51, and the angles thereof are changed.

Furthermore, in the straight flow channel 37, a middle suction chamber 40 is provided. The middle suction chamber 40 merges refrigerant gas guided from the outside to a discharge flow of the first impeller 21 and supplies the refrigerant gas to the second impeller 22. The middle suction chamber 40 is an annular space that surrounds the periphery of an inlet portion of the second impeller 22. In the inside of the middle suction chamber 40 in the radial direction, the slit-like middle suction port 41 is provided. This middle suction port 41 connects an inner portion of the middle suction chamber 40 and the straight flow channel 37 of the return flow channel.

Next, a detailed constitution of the inlet guide vane V will be described with reference to FIG. 2. As shown in the same drawing, the inlet guide vane V according to the present embodiment has a plurality of attachment portions 42S formed in the suction port 30 (suction casing 30A) and a plurality of vane main bodies 42 that is respectively supported by the attachment portions 42S.

Here, as shown in FIG. 1, the suction casing 30A (suction port 30) has an inner circumferential surface having substantially an arc shape when seen on a cross-section including the axial line As. In addition, as shown in FIG. 2, the suction casing 30A (suction port 30) has a circular cross-section when seen in the axial line As direction. That is, the suction port 30 has a suction space having a semicircular shape having one point on the axial line As as the center.

In a region which is on the inside of the suction port 30 and is farthest away from the axial line As, the attachment portions 42S for supporting the vane main bodies 42 are provided. The plurality of attachment portions 42S is arrayed in the circumferential direction with respect to the axial line As at intervals along the inner circumferential surface of the suction port 30. In the present embodiment, seven attachment portions 42S are provided in the circumferential direction at equal intervals. To these attachment portions 42S, the vane main bodies 42 are attached respectively.

As shown in FIG. 1 or FIG. 2, the vane main body 42 is a blade-like member formed into a thin plate shape. The vane main body 42 has a support portion 43 and a blade portion 44. The support portion 43 is supported by the attachment portion 42S. The blade portion 44 extends from the support portion 43 toward the inside in the radial direction with respect to the axial line As in a state of being supported by the attachment portion 42S.

The support portion 43 is attached to the attachment portion 42S so as to be capable of rotating around a revolving axial line that extends in the radial direction with respect to the axial line As. That is, the support portion 43 is a member that serves as a shaft for enabling the blade portion 44 to revolve around the revolving axial line. Meanwhile, in the following description, an axial line that extends in the radial direction with respect to the axial line As will be referred to as a radial-direction axial line Ar.

The blade portion 44 is formed so that a cross-section seen in a direction in which the radial-direction axial line Ar extends forms a blade shape. Meanwhile, in the example of FIG. 1 and FIG. 2, a state in which blade central lines Aw of the blade portions 44 are along the axial line As is shown. In the following description, the constitution of the blade portion 44 will be described on the basis of the positional relationship between the axial line As and the blade portion 44 in the above-described state.

As shown in FIG. 1, the blade portion 44 forms substantially a fan shape when seen on a cross-section including the axial line As. In other words, the blade portion 44 is formed so that the dimension in the width direction gradually decreases as the blade portion runs from the outside toward the inside in the radial direction with respect to the axial line As. An edge of the blade portion 44 on the outside in the radial direction forms substantially an arc shape so as to correspond to the spherical surface shape of the inner circumferential surface of the suction port 30. Furthermore, as shown in FIG. 2, the blade portion 44 has a tapering cross-sectional shape that gradually tapers from the outside toward the inside in the radial direction when seen in the axial line As direction.

When the vane main bodies 42 constituted as described above are respectively attached to the attachment portions 42S of the suction casing 30A, as shown in an example of FIG. 2, the vane main bodies 42 are stored on the inside of the suction casing 30A in the radial direction and are then moved toward the outside in the radial direction, thereby inserting the support portions 43 into the attachment portions 42S. More specifically, the example of FIG. 2 shows an aspect of attaching a fifth vane main body 42 in a state in which four vane main bodies 42 have been attached to the attachment portions 42S respectively. Here, among the five vane main bodies 42, the two vane main bodies from the front side in the counterclockwise direction will be referred to as a first vane main body 421 (first inlet guide vane) and a second vane main body 422 (second inlet guide vane) respectively. Furthermore, the vane main body 42 to be newly attached will be referred to as a third vane main body 423 (third inlet guide vane).

As shown in the same drawing, in a state in which other vane main bodies 42 (the first vane main body 421 and the second vane main body 422) have been already attached, there is a possibility that an end portion of the third vane main body 423 on the inside in the radial direction may interfere with the vane main bodies 42 that have been already provided. Therefore, in the case of attaching the third vane main body 423, a method in which a portion of the third vane main body 423 on the inside in the radial direction is put into a gap between the first vane main body 421 and the second vane main body 422 which the third vane main body 423 faces and is then moved toward the outside in the radial direction with respect to the axial line As, thereby being attached to the attachment portion 42S is employed.

More specifically, as shown in FIG. 11, in a production method of the centrifugal compressor 2 and an attachment method of the inlet guide vane V according to the present embodiment, first, the casing 28 and the plurality of vane main bodies 42 (the first vane main body 421, the second vane main body 422, the third vane main body 423, . . . ) are prepared (S1).

Next, the first vane main body 421 is attached (S2). In more detail, the support portion 43 of the first vane main body 421 is attached to the attachment portion 42S of the suction casing 30A.

Furthermore, the second vane main body 422 is attached to the attachment portion 42S adjacent to the attachment portion 42S to which the first vane main body 421 is attached in the circumferential direction at an interval (S3).

Next, to another attachment portion 42S provide in a region between the first vane main body 421 and the second vane main body 422 in the circumferential direction, the third vane main body 423 is attached (S4). More specifically, the third vane main body 423 is attached to an attachment portion 42S that faces the pair of attachment portions 42S and 42S to which the first vane main body 421 and the second vane main body 422 are attached in the radial direction of the axial line As. Furthermore, other vane main bodies 42 are attached to the corresponding attachment portions 42S respectively as necessary. Therefore, the inlet guide vane V is constituted.

Finally, to the casing main body 28A into which the rotary shaft 29 and the impellers (the first impeller 21 and the second impeller 22) have been already combined, the suction casing 30A is attached (S6).

Therefore, all steps of the attachment method of the inlet guide vane V and the production method of the centrifugal compressor 2 according to the present embodiment are completed.

In order to employ the above-described attachment method, the vane main body 42 (the blade portion 44) according to the present embodiment has a cross-sectional shape as shown in FIG. 3 and FIG. 4 when seen in the As direction. The blade portion 44 has a blade-like cross-sectional shape as a symmetric blade having a linearly symmetric shape having the blade central line Aw as a symmetric axis, and the thickness of the end portion on the inside in the radial direction with respect to the axial line As is set to be small.

When seen on a cross-section including the blade central line Aw, a surface on one side of the blade central line Aw is used as a pressure surface S1 which is a surface facing incoming fluid. When seen on a cross-section including the blade central line Aw, a surface on the other side of the blade central line Aw is used as a suction surface S2 which is a surface that comes into contact with fluid that flows away. That is, in the blade portion 44 as a symmetric blade, each of the pressure surface S1 and the suction surface S2 has a blade-shaped surface that runs along the surface of an imaginary blade shape Pv as a symmetric blade. Meanwhile, in the blade portion 44, the imaginary blade shape Pv is formed so as to become smaller in a similar shape as the imaginary blade shape runs from the outside in the radial direction to the inside in the radial direction.

In an end portion on the outside in the radial direction with respect to the axial line As, the support portion 43 is integrally provided. In the following description, a region of the blade portion 44 on the outside in the radial direction with respect to the axial line As will be referred to as a base end-side region A1. A region on a side opposite to the base end-side region A1 in the radial direction will be referred to as a front end-side region A2. Furthermore, the end portion of the blade portion 44 on the front end side serves as a front end surface Sn which forms a blade-shaped flat surface.

In the front end-side region A2 of the blade portion 44, a surface (thin portion-forming surface St) which recedes toward the inside of the imaginary blade shape Pv more than the surface of the imaginary blade shape Pv is formed. Meanwhile, in the present embodiment, an example in which the thin portion-forming surface St is formed on the pressure surface S1 side of the blade portion 44 will be described. However, the thin portion-forming surface St may be formed on the suction surface S2 side depending on the degree of opening (an excess opening state or a squeezing state) preferred during the operation of the compressor. In addition, the thin portion-forming surfaces St may be formed on both the pressure surface S1 and the suction surface S2.

In an end portion of the thin portion-forming surface St on the outside in the radial direction, a connection surface Sc is formed. The connection surface Sc is a curved surface which connects a level difference between the blade-shaped surface (imaginary blade shape Pv) and the thin portion-forming surface St. Specifically, the connection surface Sc is a substantial arc-shaped curved surface which connects an end portion of the base end-side region A1 on the inside in the radial direction and the end portion of the thin portion-forming surface St on the outside in the radial direction which form the blade-shaped surface. The connection surface Sc curves with respect to the blade-shaped surface so as to sink toward the inside of the blade-shaped surface.

According to the above-described constitution, the thin portion-forming surface St is formed in the front end-side region A2 of the vane main body 42. Since the thin portion-forming surface St recedes toward the inside of the imaginary blade shape Pv, the thickness dimension of the blade portion 44 in the corresponding region becomes thin. Therefore, when the plurality of vane main bodies 42 is arrayed on the inner circumferential surface of the casing (suction port) of the compressor in a state in which the front ends thereof are gathered, it is possible to easily put a vane main body 42 that is to be attached soon into a gap formed on the inside in the radial direction of the vane main bodies 42 that have been already attached.

Here, the thickness dimension of a region of the vane main body 42 on the inside in the radial direction (the dimension of the blade portion 44 in the circumferential direction with respect to the axial line As in the case of being seen in the shaft axis As direction) needs to be set to be smaller than a gap between a pair of the vane main bodies 42 which faces each other in the suction port.

On the other hand, from the viewpoint of improving the performance and efficiency of the inlet guide vane V, the thickness dimension of the vane main body 42 needs to be thick to a certain extent. In other words, when the thickness of the vane main body 42 is too thin, there is a possibility that the performance and efficiency of the inlet guide vane V may decrease.

However, in the present embodiment, the above-described constitution is employed, and thus it is possible to satisfy the performance and efficiency of the inlet guide vane V and the ease of assembly.

Furthermore, in the present embodiment, the thin portion-forming surface St is provided only in the front end-side region A2. Therefore, compared with a case in which the thickness is decreased throughout the entire blade portion 44 (the entire region including the front end-side region A2 and the base end-side region A1), it is possible to sufficiently ensure the performance and efficiency of the inlet guide vane V.

Additionally, in the present embodiment, the imaginary blade shape Pv becomes smaller in a similar shape as the blade-like cross-sectional shape runs from the outside toward the inside in the radial direction.

According to this constitution, in the region on the outside in the radial direction in which the flow rate of fluid becomes relatively faster, it is possible to relatively significantly ensure the area of the imaginary blade shape Pv. Therefore, it is possible to more effectively guide fluid and improve the efficiency of the inlet guide vane V.

Additionally, in the vane main body 42 according to the present embodiment, the pressure surface S1 has the connection surface Sc that is configured to connect the level difference between the blade-shaped surface and the thin portion-forming surface St. According to this constitution, due to the formation of the connection surface Sc, it is possible to decrease the possibility that the flow of fluid along the pressure surface S1 may separate.

Second Embodiment

Subsequently, a second embodiment of the present invention will be described with reference to FIG. 5 and FIG. 6. Meanwhile, the same constitution as in the first embodiment will be given the same reference sign and will not be described in detail.

In a vane main body 242 of the present embodiment, the thin portion-forming surface St is formed along a surface that is formed by the blade central line Aw of the imaginary blade shape Pv and the radial-direction axial line Ar. That is, in the vane main body 242, the front end-side region A2 is formed to be relatively thinner compared with the vane main body 42 in the first embodiment.

According to this constitution, the same effects as the first embodiment can be obtained, and furthermore, it is possible to improve the ease of assembly of the inlet guide vane V while maintaining the structural strength of the vane main body 42.

Third Embodiment

Next, a third embodiment of the present invention will be described with reference to FIG. 7 and FIG. 8. Meanwhile, the same constitution as in the first embodiment will be given the same reference sign and will not be described in detail.

In a vane main body 342 according to the present embodiment, the cross-sectional shape of the blade portion 44 is different from that of the vane main body 42 of the first embodiment. That is, in the vane main body 342, the thin portion-forming surface St is formed so as to extend toward the suction surface S2 as the thin portion-forming surface runs from an edge portion of the pressure surface S1 on the front end surface Sn toward the outside in the radial direction. That is, the thin portion-forming surface St extends from a front end surface Sn side toward the outside in the radial direction, then, intersects the radial-direction axial line Ar, and runs into the back side. The front end surface Sn symmetrically broadens toward both sides of the radial-direction axial line Ar from the radial-direction axial line Ar. In other words, in the vane main body 342, the front end-side region A2 is formed to be relatively thicker compared with the vane main body 42 in the first embodiment.

According to this constitution, the same effects as the first embodiment can be obtained, and furthermore, there is no case in which the vane main body 42 becomes excessively thin due to the provision of the thin portion-forming surface St. Therefore, it is possible to more sufficiently ensure the structural strength of the vane main body 42.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be described with reference to FIG. 9 and FIG. 10. In a vane main body 442 according to the present embodiment, the thin portion-forming surface St is formed on the pressure surface S1 so as to be sandwiched by the blade-shaped surface from both the inside in the radial direction and the outside in the radial direction. In other words, in the vane main body 442, the thin portion-forming surface St is formed in a position which is in the middle of extension in the radial direction on the pressure surface S1 and is far away from both a front edge and a rear edge of the blade portion 44. That is, the area of the thin portion-forming surface St is smaller compared with those in the first embodiment to the third embodiment.

According to the above-described constitution, the same effects as the first embodiment can be obtained, and furthermore, it is possible to suppress the size of the thin portion-forming surface St being smaller compared with a case in which the thin portion-forming surface St is formed throughout the entire region including the end portion on the inside in the radial direction. Therefore, it is possible to further decrease the separation of the flow of fluid caused by the formation of the thin portion-forming surface St.

Hitherto, the respective embodiments of the present invention have been described with reference to the drawings. The above-described embodiments are simply examples, and it is possible to add a variety of modifications and corrections within the scope of the gist of the present invention.

For example, in the respective embodiments described above, the inlet guide vane V that is provided in the centrifugal compressor 2 and the vane main body 42 that is used therein have been described. However, the application subjects of the inlet guide vane V and the vane main body 42 are not limited to centrifugal compressors. Regarding the application subjects of the inlet guide vane V and the vane main body 42, the inlet guide vane and the vane main body can be applied to any kinds of machines as long as the machines suction fluid thereinto and the suction amount needs to be adjusted.

Furthermore, in the respective embodiments described above, the two-stage-type centrifugal compressor 2 including two impellers has been described. However, the number of stages of the centrifugal compressor 2 is not limited thereto and may be three or more.

Additionally, in the respective embodiments described above, the descriptions have been made on the basis of the centrifugal compressor 2 including the movable vanes 50 and the driving device 51. However, the centrifugal compressor 2 does not need to include the movable vanes 50 and the driving device 51 at all times.

INDUSTRIAL APPLICABILITY

According to the inlet guide vane, it is possible to obtain sufficient performance and ease of assembly.

REFERENCE SIGNS LIST

-   -   2 CENTRIFUGAL COMPRESSOR     -   21 FIRST IMPELLER     -   22 SECOND IMPELLER     -   28 CASING     -   28A CASING MAIN BODY     -   29 ROTARY SHAFT     -   30 SUCTION PORT     -   30A SUCTION CASING     -   31 SCROLL     -   32 INNER SPACE     -   33 RETURN FLOW CHANNEL     -   34 SUCTION FLOW CHANNEL (INFLOW FLOW CHANNEL)     -   35 DIFFUSER     -   36 RETURN BEND PORTION     -   37 STRAIGHT FLOW CHANNEL     -   38 RETURN VANE     -   40 MIDDLE SUCTION CHAMBER     -   41 MIDDLE SUCTION PORT     -   42 VANE MAIN BODY     -   43 SUPPORT PORTION     -   44 BLADE PORTION     -   50 MOVABLE VANE     -   51 DRIVING DEVICE     -   242 VANE MAIN BODY     -   342 VANE MAIN BODY     -   421 FIRST VANE MAIN BODY     -   422 SECOND VANE MAIN BODY     -   423 THIRD VANE MAIN BODY     -   442 VANE MAIN BODY     -   42S ATTACHMENT PORTION     -   A1 BASE END-SIDE REGION     -   A2 FRONT END-SIDE REGION     -   Ar RADIAL-DIRECTION AXIAL LINE     -   As AXIAL LINE     -   Aw BLADE CENTRAL LINE     -   B BLADE     -   Pv IMAGINARY BLADE SHAPE     -   S1 PRESSURE SURFACE     -   S2 SUCTION SURFACE     -   Sc CONNECTION SURFACE     -   Sn FRONT END SURFACE     -   St THIN PORTION-FORMING SURFACE 

1. An inlet guide vane comprising: vane main bodies having a pressure surface and a suction surface which extend in a radial direction of a rotary shaft, wherein each of the pressure surface and the suction surface has a blade-shaped surface along a surface of an imaginary blade shape having a blade-like cross-sectional shape, and at least one of the pressure surface and the suction surface has a thin portion-forming surface which recedes toward an inside of the imaginary blade shape more than the surface of the imaginary blade shape.
 2. The inlet guide vane according to claim 1, wherein the vane main body has a front end surface on an end portion on an inside in the radial direction, the thin portion-forming surface is formed in a front end-side region connected to the front end surface on one of the pressure surface and the suction surface, and the blade-shaped surface on one of the pressure surface and the suction surface is formed in a base end-side region of the thin portion-forming surface on an outside in the radial direction.
 3. The inlet guide vane according to claim 2, wherein the thin portion-forming surface is formed along a blade central line of the imaginary blade shape.
 4. The inlet guide vane according to claim 2, wherein the front end surface forms a blade shape along the imaginary blade shape, and the thin portion-forming surface is formed so as to, as the thin portion-forming surface runs from an edge portion of one of the pressure surface and the suction surface on the front end surface toward the outside in the radial direction, extend toward the other of the pressure surface and the suction surface.
 5. The inlet guide vane according to claim 2, wherein one of the pressure surface and the suction surface has a connection surface that is configured to connect a level difference between the blade-shaped surface and the thin portion-forming surface.
 6. The inlet guide vane according to claim 1, wherein the thin portion-forming surface is formed on one of the pressure surface and the suction surface so as to be sandwiched by the blade-shaped surface from both the inside in the radial direction and the outside in the radial direction.
 7. The inlet guide vane according to claim 1, wherein the imaginary blade shape becomes smaller in a similar shape as the blade-like cross-sectional shape runs from the outside in the radial direction to the inside in the radial direction.
 8. The inlet guide vane according to claim 1, wherein, in the imaginary blade shape, the blade-like cross-sectional shape forms a linearly symmetric shape having the blade central line as a symmetric axis.
 9. A compressor comprising: the inlet guide vane according to claim 1; a casing in which a suction port that is configured to support the inlet guide vane is formed; and an impeller that is configured to compress fluid suctioned from the suction port.
 10. An inlet guide vane attachment method for attaching a plurality of inlet guide vanes to a suction port formed in a casing of a compressor in a circumferential direction of the suction port at intervals, wherein, in the inlet guide vane, each of a pressure surface and a suction surface has a blade-shaped surface along a surface of an imaginary blade shape having a blade-like cross-sectional shape, and at least one of the pressure surface and the suction surface has a thin portion-forming surface which recedes toward an inside of the imaginary blade shape more than a surface of the imaginary blade shape, the attachment method comprising: a step of attaching a first inlet guide vane to an inner circumferential side of the casing; a step of attaching a second inlet guide vane at an interval with respect to the first inlet guide vane in the circumferential direction; and a step of attaching a third inlet guide vane between the first inlet guide vane and the second inlet guide vane in the circumferential direction, wherein, in the step of attaching the third inlet guide vane, a portion of the third inlet guide vane on an inside in a radial direction which includes the thin portion-forming surface is inserted into a gap between the first inlet guide vane and the second inlet guide vane, and then the third inlet guide vane is moved to an outside in the radial direction.
 11. A centrifugal compressor production method comprising: a step of preparing the casing and the plurality of inlet guide vanes; the respective steps of the inlet guide vane attachment method according to claim 10; and a step of attaching a rotary shaft and an impeller to an inner portion of the casing. 